This invention relates to new and useful improvements in suspension systems for trucks, trailers and the like and is particularly suited for use over rough and uneven ground such as off-road conditions although of course it may be used on conventional roads as well as logging and oil well access roads.
Conventionally, such trucks and trailers are either mounted on rear wheels supported by air bags or alternatively, utilize a walking beam construction such as a Hendrickson walking beam assembly in conjunction with steel leaf springs. In this regard U.S. Pat. No. 3,653,683 R. T. Hendrickson dated Apr. 4, 1972 is relevant and is hereby incorporated by reference.
While satisfactory under normal conditions, air bags which are usually on a 1:1 ratio, have to be relatively large in order to absorb the relatively large vertical movements of the wheel assemblies under such conditions. If standard air bags are used, there is a considerable amount of bounce which occurs and which of course is detrimental both to the load being carried and to the actual suspension and chassis system of the truck or trailer.
Conventional walking beams, particularly when used under rough ground or road conditions, have traction difficulties because of the rapid changing of traction distribution which once again is particularly hard on the transmission as well as on the suspension.
The present invention overcomes these disadvantages and basically replaces the steel springs on the Hendrickson walking beam type suspension, with air bags.
In doing so, it creates a complete air suspension with various significant advantages over conventional air suspension, the single most important being almost perfect traction distribution of 25% per wheel.
Also, retention of the walking beam characteristic gives an approximate 2:1 ratio of wheel travel to air bag travel as opposed to the nearly 1:1 ratio on conventional air suspensions.
Use of walking beams in conjunction with shock absorbers that also work on a 2:1 ratio with the air bags, may assist in producing a total suspension capable of negotiating extremely rough terrain such as off-road applications, gravel hauling and the like whereas other air suspensions have neither the traction nor flexibility to function.
In accordance with the invention there is provided a walking beam wheel assembly for trucks, trailers and the like which include spaced and parallel, longitudinally extending chassis members;
said walking beam wheel assembly comprising in combination a ground engaging wheel trolley component including a pair of spaced and parallel transversely extending wheel axles with ground engaging wheels on each end thereof, a longitudinally extending walking beam extending between the wheels on each same end of said axles and means operatively connecting said walking beams one to each of said chassis members, said means including at least one air bag operatively extending between each of said beams and the corresponding chassis member.
Another advantage of the suspension is that it may be used with shock absorbers, height control valves for the air bags, and linear stabilizers all of which assist in providing a unique and very practical suspension system.
A still further advantage of the invention is to provide a device of the character herewithin described which can either be incorporated in the original construction or which is readily adapted for retro-fitting with the minimum of changes being required.
A still further advantage of the invention is to provide a device of the character herewithin described which is simple in construction, economical in manufacture and otherwise well suited to the purpose of which it is designed.
With the foregoing in view, and other advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the accompanying drawings forming a part hereof, which includes a description of the best mode known to the applicant and of the preferred typical embodiment of the principles of the present invention, in which: